Police body cameras can dramatically reduce the number of complaints against officers, research suggests.

1, When they were introduced to the American public two years ago, police body-cameras seemed like they might help everyone. Police departments liked that body cams reduced the number of public complaints about officer behavior. Communities and protesters liked that they would introduce some transparency and accountability to an officer’s actions.

2, Today, research suggests that body cameras significantly reduce the number of public complaints about police. But recent events subvert the idea that the devices help or increase the power of regular people—that is, the policed. Instead of making officers more accountable and transparent to the public, body cameras may be making officers and departments more powerful than they were before.